Bur Oak
- Zone 3
Characteristics of the tree
Bur oak (Quercus macrocarpa) is a large and majestic tree native to Canada and the US. It is an extremely adaptable oak tree, and produces mild acorns that are among the largest of all the oaks.
Bur Oaks, like most oak trees, are imposing and stately trees that bring an atmosphere of serenity to all who wander in their shade – not to mention providing edible and mild acorns to feed all the surrounding wildlife as well as humans. The bur oak is native to the eastern and central United States and Canada. It is a long lived tree capable of reaching 400 years old in the best of conditions. It can grow to up to 35 or 40 metres tall with equally large spreads, but will tend to remain smaller when growing in more northern regions. The bark is light grey/brown with deep ridges and furrows. Leaves are dark green and glossy; significantly wider at the end and tapering towards the base. Bur oaks produce the large acorns: they can be up to 1.5 inches (4 cm) long with an oblong form, with about half or three quarters of the nut covered by a burr-like cup that gives the tree its common name.
Bur Oak is also the most widely spread of the oak species thanks to its ability to thrive in such a wide range of environmental conditions. It tolerates all soil types from wide pH ranges to all different compositions and its long taproot allows it to withstand long periods of drought. It grows best in full sun but is relatively tolerant of shade in its youth. However, if it continues to be shaded, it will generally not live longer than 100 years or so. It is one of the most fire-tolerant trees due to the thickness of its bark; and even when the part above ground is killed by fire, will sprout back vigorously from the base.
Bur Oak is an outstanding shade tree and is ideal for urban plantation due to its tolerance of air pollution and salt. Its hardiness (as far north as zone 3) and long life make it a popular choice for shelterbelts, and its ability to thrive in poor soils also makes it a great choice for reclamation of degraded sites. It does not produce acorns every year, but every three years or so. When it does, it is extremely productive. Bur oak acorns are not only the largest but also considered to be one of the mildest and best tasting acorns, though the tannins should still be leached out (by boiling several times, changing the water each time) before consumption. Even if you do not intend to consume them yourself, however, they will enormously benefit the local wildlife. Bur oak is also a good timber tree, with its wood used for beams, boards, railroad ties, furniture, and floors.
Bur Oak grows at a moderate rate and reaches around 20 metres in height in northern climates, with a spread of 10 metres. (In warmer climates, it can grow larger and taller, up to 35 metres in height). This illustration shows a 20-year-old bur oak, that has reached 6m (20 feet) in height.
You should note that this illustration is meant only to give a general indication of what you can expect, and the growth of your tree might look somewhat different. The development of a tree depends on the soil type, irrigation, fertilisation and climatic conditions.
What we show here is based on our observation of the growth of the bur oak in zone 4, in rather poor soil. In a colder climate it might be slower, and in richer soil or warmer climates it might be faster.
All our bur oak trees are sold bare-root, without pots. They have been cultivated directly in our soil. Bare-root trees must be taken out of the ground and shipped during their period of dormancy, which is why we only ship trees in the spring. A big advantage with these kinds of trees is that they take up very little space, and can therefore be easily shipped by mail all over Canada!
This photograph shows a 1-3-foot bur oak tree, just like one that you might receive. Depending on the height you choose at the time of purchase, the tree might be somewhat taller (3-5 feet).
